I think the best thing to do is keep it simple.

If you first learn a bit about basic composition as suggested above that will help most pictures look good - rarely anything placed in the center of the frame looks right - it is much better if it is placed on one of the 4 intersections - to do this, focus on your subject, hold the shutter half press and recompose - that way it will be in focus when you full press the shutter.

You have a very capable DSLR camera - read the manual and learn how to 'creatively' alter the aperture and shutter for different effect, do a bit of web searching and learn about apertures - try and get some images of Sam with a shallow depth of field and then with a deep depth. Get him running around and play with shutter speed - getting sharp images and then some that show motion blur....if nothing else, it'll tire him out near bed time

Try and use the modes 'A - S - M' on the dial on the top of the camera as these will let you control the effect you want exactly.

Any more help, feel free to ask in the forums or PM me if you like.
regards, Kevin